Popular smoking articles, such as cigarettes, have a substantially cylindrical rod shaped structure and include a charge, roll or column of smokable material such as shredded tobacco (e.g., in cut filler form) surrounded by a paper wrapper thereby forming a so-called “tobacco rod.” Normally, a cigarette has a cylindrical filter element aligned in an end-to-end relationship with the tobacco rod. Typically, a filter element comprises plasticized cellulose acetate tow circumscribed by a paper material known as “plug wrap.” Certain cigarettes incorporate a filter element having multiple segments, and one of those segments can comprise activated charcoal particles. Typically, the filter element is attached to one end of the tobacco rod using a circumscribing wrapping material known as “tipping paper.” It also has become desirable to perforate the tipping material and plug wrap, in order to provide dilution of drawn mainstream smoke with ambient air. A cigarette is employed by a smoker by lighting one end thereof and burning the tobacco rod. The smoker then receives mainstream smoke into his/her mouth by drawing on the opposite end (e.g., the filter end) of the cigarette.
The tobacco used for cigarette manufacture is typically used in a so-called “blended” form. For example, certain popular tobacco blends, commonly referred to as “American blends,” comprise mixtures of flue-cured tobacco, burley tobacco and Oriental tobacco, and in many cases, certain processed tobaccos, such as reconstituted tobacco and processed tobacco stems. The precise amount of each type of tobacco within a tobacco blend used for the manufacture of a particular cigarette brand varies from brand to brand. However, for many tobacco blends, flue-cured tobacco makes up a relatively large proportion of the blend, while Oriental tobacco makes up a relatively small proportion of the blend. See, for example, Tobacco Encyclopedia, Voges (Ed.) p. 44–45 (1984), Browne, The Design of Cigarettes, 3rd Ed., p.43 (1990) and Tobacco Production, Chemistry and Technology, Davis et al. (Eds.) p. 346 (1999).
Oriental tobaccos are desirable components of the tobacco blends of smoking products because Oriental tobaccos yield smoke possessing certain unique and desirable flavor and aroma characteristics. Most Oriental tobaccos possess relatively low nicotine content, and possess relatively high levels of certain reducing sugars, acids and volatile flavor compounds. Some of the distinct flavors and aromas characteristic of Oriental tobacco smoke are attributed to the presence of sucrose esters in Oriental tobaccos, and the pyrolysis products of those sucrose esters. The sucrose ester concentrations in some types of Oriental tobaccos are relatively high, and those sucrose esters are precursors to compounds that introduce so-called “off-notes” to the flavor and aroma of smoke that results from the burning of those tobaccos. Thus, there have been constraints upon the amount of certain Oriental tobaccos traditionally used in tobacco blends, because the desirable flavor and aroma characteristics of the smoke of those tobaccos become overpowering and undesirable when relatively high levels of those tobaccos are used in tobacco blends.
The types of sucrose esters that are present in Oriental tobaccos are sugar derivatives possessing covalently bound carboxylic acid groups. Sucrose esters typically present in Oriental tobaccos include those that can be represented by the following formula:
where R is C3–C8 carboxylate and R′ is acetate. See, also, Tobacco Production, Chemistry and Technology, Davis et al. (Eds.) p. 294 (1999). Sucrose esters thermally decompose (e.g., such as when the Oriental tobacco incorporating those sucrose esters is burned) to yield branched chain low molecular weight carboxylic acids, including 2-methylpropionic acid, 3-methylbutyric acid and 3-methylpentanoic acid. Many of the off-notes characteristic of the smoke of Oriental tobaccos (e.g., those that are characterized as being “cheesy” or likening “sweaty sock” in nature) are associated with those carboxylic acids.
It would be desirable to provide a method for altering the sucrose ester concentration within a tobacco blend incorporating an Oriental tobacco. In particular, it would be desirable to provide tobacco blends incorporating Oriental tobaccos that when burned, such as during the use of smoking articles incorporating those blends, would provide optimized flavor and aroma characteristics associated with the pyrolysis products of sucrose esters.